10.1
What is transferred between objects when they rub against each other, and why are only these particles transferred?
Electrons are transferred because they have a small mass and are relatively far from the nucleus.
What are the three laws of electric charges?
1. Like charges (same) repel
<- (+) (+)-> , <- (-) (-)->2. Opposite charges attract
(+)-> <-(-)
3. Charged and neutral objects attract each other
(+)-> <-() , (-)-> <-()
What is a lightning rod and describe the two functions of a lightning rod.
lightning rod a metal sphere or point, attached to the highest part of a building and connected to the ground
A lightning rod has two functions: to reduce the likelihood of a lightning strike and, if a strike occurs, to conduct the charge safely to the ground.
What’s the difference between an insulator and conductor?
insulator a material in which electrons cannot move easily from one atom to another conductor a material in which electrons can move easily between atoms
How do the net charge and distance of an object affect its electric field, and at what speed are electric forces between two objects transmitted?
Objects with greater net charges have stronger electric fields. The greater the distance from a charged object, the weaker the electric field of the object is. Also, all electric forces between two objects are transmitted through the electric field at the speed of light.
Briefly describe a Van de Graff generator and two of its uses.
Van de Graaff generator a device that accumulates very large charges
Van de Graff generators have been used in atom smashers.
(Bonus) A Van de Graff generator can accelerate particles to very high speeds. Beams of high-speed particles can be focussed so they crash into each other, breaking the particles into fragments and sometimes forming new subatomic particles.
Van de Graaff generators have also been used to test the electronic circuits used in space technology.
Why are most objects electrically neutral, and what happens when two neutral objects made of different materials come into contact with each other?
Most objects are electrically neutral because they contain equal numbers of positively charged protons and negatively charged electrons. When two neutral objects made of different materials rub against each other, electrons transfer from one material to the other.
Describe the 3 methods of charging - charging by friction (page 403) , charging by contact(page 412), and charging by induction (page 415).
charging by friction a process in which objects made from different materials rub against each other, producing a net static charge on each
charging by contact generating a charge on a neutral object by touching it with a charged object
The third method of charging is charging by induction. When a charged object is close to a neutral object, the electric field of the charged object produces a force on the neutral object.
How does an electrostatic precipitator reduce pollution?
It’s because an electrostatic precipitator is a type of cleaner that removes unwanted particles and liquid droplets from a flow of gas. An electrostatic precipitator can be very effective for reducing pollution and waste.
What happens when an object becomes charged by friction
When objects become charged by friction, one material has a stronger attraction to electrons (which are negatively charged) than another material, and therefore pulls electrons off the material that has the weaker attraction for them. As a result, both materials become charged due to an excess or a deficit (shortage) of electrons.
You can charge a balloon by rubbing it against your clothing. Then you can stick the charged balloon to a wall.
a) Is the wall charged by contact or by induction? Explain.
b) Why does the balloon eventually fall from the wall?
a) The wall is charged by induction.
- When you bring the negatively‑charged balloon near the wall, the excess electrons in the wall’s surface are repelled, leaving a thin layer of positive charge on the wall’s surface. This induced positive charge attracts the balloon and allows it to stick, even though the wall itself remains overall neutral.
b) The balloon eventually falls because the induced charge on the wall slowly neutralizes
- Over time, stray ions in the air (or moisture) conduct the excess charge away, reducing the attractive force.
- Also, the balloon may lose its own charge through leakage to the air or contact with other surfaces, weakening the attraction until gravity pulls it down.
What is a radiation dosimeter ?
A small device that detects and measures exposure to radiation